The present invention is related to a communication network comprising a plurality of secondary nodes being coupled to at least one primary node, said secondary nodes being arranged for transmitting packets to the primary node according to predetermined transmission properties.
The present invention is also related to a node for use in such a communication network and a communication method.
A communication network according to the preamble is known from the conference paper xe2x80x9cA Hybrid Multiplexing Scheme for Multi-Service Networksxe2x80x9d published in the proceedings of SPIE conference on Broadband Access Networks, Vol. 2917, Boston, November 1996.
There is an increasing interest in switched broadband networks to offer various services to subscribers connected to such networks. Possible services are Broadcast TV, Video on Demand, Video conferencing, telephony and fast Internet access. One of the most promising solutions for realizing such a network is a so-called Hybrid Fiber Coax (HFC) network. Standardization of these broadband networks is done in IEEE802.14, DVB and DAVIC.
In order to provides services having quite different properties such networks can be based on ATM. In ATM the information to be transmitted is subdivided in fixed length packets with a 5 byte header and a 48 byte payload area. In ATM the possibility exists to transmit different types of packets (audio, video and data) using different transmission properties, also called Quality of Service types. For real time video communication, a high bit rate and a low delay are required. For video broadcast a high bitrate is required, but some delay can be tolerated. In both cases a Constant Bit Rate connection is required, each with different delay requirements. For real time audio transmission the bitrate can be lower, but the delay requirements are substantially the same. For data communication such as file transfer a lower bitrate can be tolerated, and almost no delay requirements have to be fulfilled.
In the above mentioned prior art document it is not disclosed how the required transmission properties are associated with packets to be transmitted to the primary node.
An object of the present invention is to provide a communication network according to the preamble in which the required transmission properties are associated in an easy way with the packets to be transmitted to the primary node.
To achieve said object, the communication network according to the invention is characterized in that the secondary node comprises selection means for selecting packets according to address information in their header, and in that the transmission means are arranged for transmission of said packets with transmission properties dependent on the selection performed by the selection means.
By selecting packets according to their address information and assigning transmission properties according to said address information, the transmission properties are associated with the packets to be transmitted in an easy and effective way.
An embodiment of the communication network according to the invention is characterized in that in that the secondary node comprises address translation means for translating initial address information carried by packets received from at least one terminal device into said address information carrying information about the transmission properties to be used for transmitting the associated packets.
This embodiment of the communication network allows it to be interfaced to terminal devices which are being addressed in a standard way. This standard way can be the way terminal devices are addressed in a public ATM network. By translating the standard address into an address comprising information about the transmission properties to be used, the terminals can still be identified in a standard way. The address assigned to a secondary terminal in such a core network is translated into an address suitable for use in the network according to the invention. By identifying the transmission resource by a first part of the address information, the signal can be directed into the proper part of the network. The second part of the address information can be used to direct the further routing in the network.
A further embodiment of the communication network according to the invention is characterized in that the communication network comprises further address translating means for translating said address information back into the address information present in the packets received by the secondary nodes from said terminal device.
By introducing additional address translating means for translating the translated address part back into the address information present in the packets received from the terminal devices, it is obtained that the communication network according to the invention is fully transparent between the input of the secondary node and the output of the primary node.
A further embodiment of the communication network according to the invention is characterized in that the communication network comprises cross connect means for passing packets from the secondary nodes to an outside network, and in that the further address translating means are arranged for translating the address information before the packets are applied to the cross connect means.
By positioning the further address translation means between a cross connect and the rest of the network, the network specific address information can be used in the complete network except the connections to a core network and the connections to the terminal units.